Apparatus for making drawings



Nov. 10, 1953 c. L. Y. PARKER ETAL ,3

APPARATUS FOR MAKING DRAWINGS 5 Sheets-Sheet 1 Filed June 4, 1948 Fig.l

' Inventors: MJLGIIIMdMbOZOUgkPGI'IiGI; cfiarlesm'lliam Elm? Nov. 10, 1953 c. L. Y. PARKER ETAL 2,658,

APPARATUS FOR MAKING DRAWINGS 3 Sheets-Sheet 2 Filed June 4, 1948 Inventars: Charles Lamond )fzrborough Parller Charles Willmm Emezyw Tonzfirzan Smzth 13y v M Horncys Fig.3

Nov. 10,1953 c. L. Y. PARKER ETAL APPARATUS FOR MAKING DRAWINGS 5 Sheets-Sheet 3 Filed June 4, 1948 fiwentara: arleslamondfizrborougb Par/(e 1; flarleskl'llian Emerygtl YbnzBrianSmlf/L MM; v M

' A forncys Patented Nov. 10, 1953 APPARATUS FOR MAKING DRAWINGS Charles Lamond Yarborough Parker, Crowborough, Charles William Emery, Surbiton, and Tom Brian Smith, Petts Wood, England, assignors to Minister of Supply in His Majestys Government of the United Kingdom of Great Britain and Northern Ireland, London, England Application June 4, 1948, Serial No. 31,024

Claims priority, application Great Britain June 18, 1947 11 Claims.

In the making of maps by ground survey, there is always some difliculty, when covering a large area or working on a large scale, in working continuously from one sheet of paper to another and inaccuracies are sometimes liable to be introduced by the methods which must be used. The problem is aggravated by the limitations which practical considerations impose on the size of drawing surface which may conveniently be used and handled in the field.

An object of the present invention, therefore, is to provide a device which gives in effect the facility of a drawing surface which may be extended indefinitely in any direction as desired, while ensuring accurat registration between successive sections from which the surface is built up.

A further object of the invention is to provide a device having the feature of the preceding paragraph and yet being compact and manageable in form. Other objects of the invention are to provide a device of this kind in which a drawing surface is provided free from obstructive fastening devices, which might interfere with the use of drawing instruments such as rulers, scales or protractors on th drawing surface.

According to this invention, therefore, an apparatus for providing an extendable drawing surface from a plurality of rigid plates each having a face adapted to receive impressions to be made thereon, with an appropriate writing instrument, comprises a bed and means for holding on it a plurality of such plates in co-planar edge-to-edge relationship.

Preferably the apparatus comprises a bed or base plate of suitable size and shape, clamping means for engaging the plates edgewise and loeating them in proper edge-t-o-edge relation, and holding means for retaining the plates in contact with the bed. The clamping means preferably comprise spring-urged fingers adapted to urge the plates towards one another and towards one corner of the bed; and preferably also the means for holding the plates in contact with the bed comprise means such as suction cups of rubher or lik suitable material, engaging the rear or under surfaces of the plates. The bed is preferably square in shape and of suitable size to receive four square plates of equal size to one another.

The bed may be recessed and the recessing is on at least one face to provide a surface on which drawings may be made in pencil or in ink.

When the apparatus is to be used for mapmaking, the plates may be made of such size in relation to the scale on which the map is to be drawn, that the edges of the plates may be made to coincide with national grid or other arbitrary dividing lines.

From the foregoing it will be understood that if a drawing area of, say, four plates is provided by the apparatus, an extension of the drawing area may be made in any direction by removing two of the plates adjoining the edge of the frame remote from that beyond which the work is to be extended, moving the remaining two plates into the positions thus vacated, and inserting two fresh plates in their places. Combinations of two or more plates may be provided according to requirements, it being understood that if only two plates or three plates arranged in line are provided, extension of the drawing area in only one direction (or its reverse) is possible, although, obviously in such a case this direction may be turned through a right angl by turning one plate, from which the extension is required, through a right angle. The greatest utility will normally be obtained, however, with square arrangements of plates.

In order that the invention may be more clearly understood and readily carried into effect, an

embodiment thereof, comprising a frame or holder for holding a group of four plates, will now be described with reference to the accompanying drawings in which:

Fig. 1 is a plan view and Fig. 2 is an inverted plan view of the holder according to the invention.

Fig. 3 is a section on the line IIIIII of Fig. 2 of a detail.

Fig. 4 is an exploded view of a part of the mechanism, as seen from below.

Referring now to the drawings, the holder comprises a bed or base plate I, mounted on a wooden frame 2, around which is a protective rubber buffer 3. Secured to the upper surface of the base plate I, is a frame 4, the thickness of which is equal to or slightly less than that of the plates to be held in the device. O two adjacent sides of the frame 4, locating projections or steps 5 are provided at intervals. These projections 5 are accurately machined so that the inner edges of the projections on each side are in line, the lines defined by the projections of the two sides Projecting through the frame 4 on the two other adjacent sides are four fingers 6, two on each side. Those fingers do not extend above the frame 4, but project suillciently above the surface of the base plate I to engage the edges of surface plates placed on the base plate. The plates are shown in dotted lines in Fig. 1. The fingers 6 are controlled by a mechanism to be described later in such a manner, that they may be withdrawn into recesses 'I in the frame 4 out of engagement with the surface plates, as shown in Fig. 1, or may be released so as to be springurged inwardly of the frame to engage surface plates placed on the base plate and press them towards and into engagement with one another and with the projections 5, whereby they are accurately located with respect to one another. A lever B projecting from one corner of the frame and movable in the direction of the arrow provides for control of the fingers 6 in the manner hereinafter described. 1

In order to hold the plates down in contact with the base plate, rubber suction cups 9 are provided, mounted on spiders III on the rear of the base plate in register with holes made in the base" plate, and so located as to engage centrally each plate of a set of four plates (not shown) filling the frame. The details of one of these suction cups are shown in the sectional view of Fig. 3. The rubber cup 9 has an integrally molded central boss II on its rear surface in which is molded as a metal insert an axially projecting metal stem I2, which passes through a hole in a cup I3 mounted at the centre of the supporting spider III. A spring I4 surrounding the stem I 2 engages the bottom of the cup I3, and f.

the head of a thimble I5, fixed to the top of the stem I2 by means of a cross pin I6, and serves therefore, to urge the centre of the cup 9 upwardly (as seen in the drawing) away from the base plate I. It will now be seen that when the cup 9 is pressed into engagement with the rear surface of a plate placed on the base plate I, by pressing on the thimble I5 and then released, the centre of the cup is drawn away from the surface of the plate setting up suction within the cup, which serves to hold the plate in position, by pulling it down on to the surface of the base plate. The suction can be made more effective by first coating the rear surface of the plate with glycerine so that an airtight seal is obtained between the edge of cup 9 and the surface of the plate.

The operation of. the fingers 6, will be more readily understood by reference to the exploded view of a part of the mechanism shown in Fig. 4.

Each finger 5 comprises an arm I6 at right angles to the finger, which lies on the rear of the base plate I. This arm I6 slides in a channel groove in a block I! fixed to the base plate, an upstanding peg I8 on the arm passing through a slot I9 provided in the block and extending in a direction at right angles to the edge of the base plate I. Rotatably mounted on the block I1, is a disc 20, having a radial notch 2 I, which engages the peg I l with a loose sliding fit. A second radial notch 22 in the disc 20, at right angles to the notch 2 I, engages a peg 23 provided on an actuating arm 24, which extends down one side of the frame and serves to actuate both of the fingers on that side. A similar actuating bar 25 is provided for the other two fingers on the other side of the frame.

In the corner of the frame is a rotatably mounted disc 26, having two radial slots 21 and 28 arranged at right angles to oneanother. Pegs 29 and 30 on the ends of actuatingarms 24 and 25 respectively engage in these slots so that rotation of the disc 26 produces simultaneous longitudinal movements of the two actuating arms.

The disc 26 is turned by means of the peg 2|, which projects upwardly from the lever 8 and engages in slot 21 in the disc 28. The arm I is pivotally mounted at its inner end on the base plate I. It is maintained in either of its extreme positions by means of a dead centre spring 32 (Fig. 2), which extends between the peg 3| and the peg 33 mounted on the base plate and protruding through a hole 34 in the disc 26.

All the fingers 6 are spring-urged inwardly oi' the frame by springs 35 extending between the upper ends of pegs I8 and pegs 36 mounted on the base plate.

It will now be seen that the operation of the device is as follows. With the parts in the position shown, the fingers 6 are all withdrawn outwardly of the frame so that surface plates may be placed in position in the frame. The lever B is now moved round in the direction of the arrow into the locked position, into which it is urged by the spring 32 as soon as dead centre" is passed. Moving the lever 8 turns the disc 26 thus moving actuating bar 24 upwardly (as seen in Fig. 2) and bar 25 to the right (as seen in Fig. 2). This turns discs 20 on the right hand side of the frame as swn in Fig. 2 anti-clockwise, thus enabling the corresponding fingers 6 to engage the edges of the surface plates and urge them towards one another and against locating projections 5 on the far side of the frame. Similarly the discs 20 on the top side of the frame as seen in the drawing are turned clockwise and the corresponding fingers 6 are moved inwardly oi the frame to urge the surface plates towards one another and against the locating projections 5 on the far side of the frame.

The plates having thus been accurately located are secured in place by engaging the suction cups 9 with their rear surfaces by pressing and releasing the thimbles II. The plates will thus be drawn firmly down onto the base plate and will be firmly held in position thereon.

We'claim:

1. Portable drawing apparatus comprising a bed having a plurality of apertures therein, a suction device in each of said apertures, each suction device having a cup formed of resilient material engageable with a sheet of drawing material, the said cup being evacuated solely by its own deformation when pressure is exerted between the cup and the sheet, so that a plurality of said sheets may be held on to said bed to main tain them in co-planar relationship, and means for engaging said sheets in edge-to-edge contact with one another.

2. Portable drawing apparatus according to claim 1 including resilient means urging said suction devices in a direction to pull said sheets down on said bed.

3. Portable drawing apparatus according to claim 2 including manually operable means for moving each of said suction devices individually into operative engagement with a corresponding sheet on said bed against the action of said resilient means.

4. Portable drawing apparatus comprising a bed, suction means for holding on to said bed a plurality of sheets of drawing material to maintain them in co-planar relationship, said suction means comprising a series of cups formed of resilient material, each cup being evacuated solely by its own deformation when pressure is exerted between the cups and the sheets, and means for holding said sheets in edge-to-edge contact with one another.

5. Portable drawing apparatus comprising a bed, means for holding on said bed a plurality of sheets of drawing material to maintain them in co-planar relationship, said means comprising suction devices each of which is in the form of a cup made from resilient material and each of which is evacuated solely by its own deformation when pressure is exerted between the cups and the sheets, spaced sheet-engaging stops aligned along each of two adjacent sides of said bed, and spaced sheet-engaging members aligned along each of two sides of said bed opposite said firstmentioned sides, said members engaging edges of at least some of said sheets to hold edges of at least some of said sheets against said stops to maintain said sheets in edge-to-edge contact with one another.

6. Portable drawing apparatus according to claim 5 including manually operable means to move said sheet-engaging members away from said sheets.

7. Portable drawing apparatus according to claim 5 including resilient means urging said members against said sheets, and manually operable means moving said members away from said sheets against the action of said resilient means.

8. Portable drawing apparatus comprising a bed having a plurality of apertures therein, a suction cup made from resilient material associated with each of said apertures, manually operable means for moving each of said suction cups individually in said apertures to engage a corresponding one of a plurality of rectangular sheets of drawing material on said bed, the said cups being evacuated solely by their own deformation when pressure is exerted between the cups and the sheets, resilient means urging said. suction cups in a direction to pull said sheets on to said bed to maintain them in co-planar relationship, spaced sheet-engaging stops aligned along each of two adjacent sides of a rectangle on said bed, spaced sheet-engaging members aligned along each of the two other sides of said rectangle, resilient means urging said sheet-engaging members into engagement with outer edges of at least some of said sheets and thus at least some of said sheets against said stops, to maintain said sheets in edge-to-edge contact, and manually operable means moving said sheetengaging members away from said sheets against the action of said resilient means.

9. Portable drawing claim 8 in which said members are disposed on the sides of a square to receive four square sheets of drawing material, there being a suction cup disposed to engage each of the four square sheets.

10. Portable drawing apparatus for providing an extensible drawing surface and adapted for use with a number of rigid sheets of drawing material, comprising a bed for receiving the rigid sheets, means carried by said bed for urging the rigid sheets against one another in edge-to-edge contact, and resilient suction cups individual to each rigid sheet, the said cups being evacuated solely by their own deformation when pressure is exerted between the cups and the sheets, and being associated with said bed and acting on the rear surface of the rigid sheets for holding said sheets on to said bed so that a virtually continuous and unobstructed drawing surface is estab-' lished.

11. Portable drawing apparatus comprising in combination a bed, a plurality of sheets of anodized aluminum adapted to lie on said bed, said sheets thereby presenting a surface suitable for drawing upon, means for urging said sheets in edge-to-edge contact with one another, and suction cups on said bed acting on the rear surface of said sheets for holding said sheets on to said bed, each of the said cups being evacuated solely by its own deformation when pressure is exerted between the cups and the sheets.

CHARLES LAMOND YARBOROUGH PARKER. CHARLES WILLIAM EMERY. TOM BRIAN SMITH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 563,931 Laughlin et a1. July 14, 1896 863,988 Hansen Aug. 20, 1907 1,199,280 Krumming Sept. 26, 1916 1,225,305 Barnard May 8, 1917 1,261,223 Eaton Apr. 2, 1918 1,439,815 Haugh Dec. 26, 1922 1,508,733 Trabold Sept. 16, 1924 1,519,965 Hovhannessian Dec. 16, 1924 1,851,028 Worrall Mar. 29, 1932 2,198,765 Featherstone et a1. Apr. 30, 1940 2,414,606 Page Jan. 21, 1947 2,425,921 Crockett Aug. 19, 1947 apparatus according to sheet-engaging stops and 

